The present invention provides substituted pyrazole derivatives of formula (I)which are therapeutically useful as selective CDK12/13 inhibitors. These compounds are useful in the treatment and/or prevention of diseases and/or disorders associated with CDK12/13 in a mammal. The present invention also provides preparation of the compounds and pharmaceutical compositions with at least one of the substituted pyrazole derivatives of formula (I) or a pharmaceutically acceptable salt, an N-oxide or a stereoisomer thereof.